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118 lines
3.6 KiB
C++
118 lines
3.6 KiB
C++
// dbhelpers.h
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/**
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* Copyright (C) 2008 10gen Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License, version 3,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/* db helpers are helper functions and classes that let us easily manipulate the local
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database instance.
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*/
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#pragma once
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namespace mongo {
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struct Helpers {
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/* ensure the specified index exists.
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@param keyPattern key pattern, e.g., { ts : 1 }
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@param name index name, e.g., "name_1"
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This method can be a little (not much) cpu-slow, so you may wish to use
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OCCASIONALLY ensureIndex(...);
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Note: use ensureHaveIdIndex() for the _id index: it is faster.
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Note: does nothing if collection does not yet exist.
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*/
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static void ensureIndex(const char *ns, BSONObj keyPattern, bool unique, const char *name);
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/* fetch a single object from collection ns that matches query.
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set your db SavedContext first.
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@param requireIndex if true, complain if no index for the query. a way to guard against
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writing a slow query.
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@return true if object found
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*/
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static bool findOne(const char *ns, BSONObj query, BSONObj& result, bool requireIndex = false);
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/* Get/put the first object from a collection. Generally only useful if the collection
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only ever has a single object -- which is a "singleton collection".
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You do not need to set the database before calling.
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Returns: true if object exists.
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*/
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static bool getSingleton(const char *ns, BSONObj& result);
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static void putSingleton(const char *ns, BSONObj obj);
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/* Remove all objects from a collection.
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You do not need to set the database before calling.
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*/
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static void emptyCollection(const char *ns);
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};
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class Database;
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/* Set database we want to use, then, restores when we finish (are out of scope)
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Note this is also helpful if an exception happens as the state if fixed up.
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*/
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class DBContext {
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Database *olddb;
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string oldns;
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public:
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DBContext(const char *ns) {
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olddb = cc().database();
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oldns = cc().ns();
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setClient(ns);
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}
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DBContext(string ns) {
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olddb = cc().database();
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oldns = cc().ns();
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setClient(ns.c_str());
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}
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/* this version saves the context but doesn't yet set the new one: */
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DBContext() {
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olddb = cc().database();
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oldns = cc().ns(); }
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~DBContext() {
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cc().setns(oldns.c_str(), olddb);
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}
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};
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// manage a set using collection backed storage
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class DbSet {
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public:
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DbSet( const string &name = "", const BSONObj &key = BSONObj() ) :
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name_( name ),
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key_( key.getOwned() ) {
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}
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~DbSet();
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void reset( const string &name = "", const BSONObj &key = BSONObj() );
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bool get( const BSONObj &obj ) const;
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void set( const BSONObj &obj, bool val );
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private:
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string name_;
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BSONObj key_;
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};
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} // namespace mongo
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